diff --git a/editor/js/ui/common/typedInput.js b/editor/js/ui/common/typedInput.js
index 90749d509..2bfea5e18 100644
--- a/editor/js/ui/common/typedInput.js
+++ b/editor/js/ui/common/typedInput.js
@@ -36,7 +36,7 @@
                         return false;
                     }
                     // Next char is a-z
-                    if (!/[a-z0-9]/i.test(str[i+1])) {
+                    if (!/[a-z0-9\$\_]/i.test(str[i+1])) {
                         return false;
                     }
                     start = i+1;
diff --git a/red/runtime/util.js b/red/runtime/util.js
index f132564c8..cae03a4be 100644
--- a/red/runtime/util.js
+++ b/red/runtime/util.js
@@ -161,7 +161,7 @@ function normalisePropertyExpression(str) {
                     throw new Error("Invalid property expression: unterminated expression");
                 }
                 // Next char is a-z
-                if (!/[a-z0-9]/i.test(str[i+1])) {
+                if (!/[a-z0-9\$\_]/i.test(str[i+1])) {
                     throw new Error("Invalid property expression: unexpected "+str[i+1]+" at position "+(i+1));
                 }
                 start = i+1;
diff --git a/test/red/runtime/util_spec.js b/test/red/runtime/util_spec.js
index aa8e25728..9a4dbe37c 100644
--- a/test/red/runtime/util_spec.js
+++ b/test/red/runtime/util_spec.js
@@ -333,6 +333,11 @@ describe("red/util", function() {
         it("pass a['a.b[0]'].c",function() { testABC("a['a.b[0]'].c",['a','a.b[0]','c']); })
         it("pass a[0][0][0]",function() { testABC("a[0][0][0]",['a',0,0,0]); })
 
+        it('pass a.$b.c',function() { testABC('a.$b.c',['a','$b','c']); })
+        it('pass a["$b"].c',function() { testABC('a["$b"].c',['a','$b','c']); })
+        it('pass a._b.c',function() { testABC('a._b.c',['a','_b','c']); })
+        it('pass a["_b"].c',function() { testABC('a["_b"].c',['a','_b','c']); })
+
         it("fail a'b'.c",function() { testInvalid("a'b'.c"); })
         it("fail a['b'.c",function() { testInvalid("a['b'.c"); })
         it("fail a[]",function() { testInvalid("a[]"); })